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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2000.258 -- RHSA-2000:058-03 Format string exploit in screen 18 September 2000 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: screen Vendor: Red Hat Operating System: Red Hat Linux 5.2 and earlier Linux Platform: N/A Impact: Root Compromise Access Required: Local - --------------------------BEGIN INCLUDED TEXT-------------------- - --------------------------------------------------------------------- Red Hat, Inc. Security Advisory Synopsis: Format string exploit in screen Advisory ID: RHSA-2000:058-03 Issue date: 2000-09-07 Updated on: 2000-09-07 Product: Red Hat Linux Keywords: screen exploit format Cross references: N/A - --------------------------------------------------------------------- 1. Topic: Security hole in screen in Red Hat Linux 5.2 and earlier releases 2. Relevant releases/architectures: Red Hat Linux 5.2 - i386, i586, i686, alpha, sparc, sparc64, sparcv9 3. Problem description: Screen allows the user to overload the visual bell with a text message that can be set by the user. This text message is handled as a format string, instead of as a pure string, so maliciously written format strings are allowed to overwrite the stack. Since screen in Red Hat Linux 5.2 and earlier releases was setuid root, this security hole could be exploited to gain a root shell. 4. Solution: For each RPM for your particular architecture, run: rpm -Fvh [filename] where filename is the name of the RPM. 5. Bug IDs fixed (http://bugzilla.redhat.com/bugzilla for more info): N/A 6. RPMs required: Red Hat Linux 5.2: sparc: ftp://updates.redhat.com/5.2/sparc/screen-3.7.4-4.sparc.rpm alpha: ftp://updates.redhat.com/5.2/alpha/screen-3.7.4-4.alpha.rpm i386: ftp://updates.redhat.com/5.2/i386/screen-3.7.4-4.i386.rpm sources: ftp://updates.redhat.com/5.2/SRPMS/screen-3.7.4-4.src.rpm 7. Verification: MD5 sum Package Name - -------------------------------------------------------------------------- 106a9d1487815b84307182b6ace4eddd 5.2/SRPMS/screen-3.7.4-4.src.rpm 40d13c23ade8c8e9117dd7ff6c9723c9 5.2/alpha/screen-3.7.4-4.alpha.rpm 06bc8d4a829aee9cc21696aaa611771a 5.2/i386/screen-3.7.4-4.i386.rpm 6501aefe36c2f38cc1337c14141b0993 5.2/sparc/screen-3.7.4-4.sparc.rpm These packages are GPG signed by Red Hat, Inc. for security. Our key is available at: http://www.redhat.com/corp/contact.html You can verify each package with the following command: rpm --checksig <filename> If you only wish to verify that each package has not been corrupted or tampered with, examine only the md5sum with the following command: rpm --checksig --nogpg <filename> 8. References: N/A Copyright(c) 2000 Red Hat, Inc. - --------------------------END INCLUDED TEXT-------------------- This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to use any or all of this information is the responsibility of each user or organisation, and should be done so in accordance with site policies and procedures. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the original authors to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/Information/advisories.html If you believe that your system has been compromised, contact AusCERT or your representative in FIRST (Forum of Incident Response and Security Teams). Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBOlSMzCh9+71yA2DNAQF9PQP8C8JNyERyh19IKB0iEmuSQtBt80lWq9AN 8T+CVKN77PaWpnRrpJ3DCLIGddzNCPV5kvWIx7qzJWo6dh4qaRhuc5fF7YmbsjB5 eyyvkgtkmdgXhdKlPIxmnzOqosTIUQ46AlY3XyhK1M8udS3dgyerstfm2Ig30Kke wZxP6BCZHyc= =0MEI -----END PGP SIGNATURE-----